1. Field of the Invention
The present invention relates to an automatic electronic parts-mounting apparatus for taking electronic parts out of a parts feeder by use of an adsorptive nozzle, also known as a suction nozzle and determining an angular position of the electronic parts by the rotation of the adsorptive nozzle to mount them on a printed substrate.
2. Description of the Related Art
As a conventional technique for automatically and continuously mounting electronic parts on a printed substrate during manufacturing processes, parts being supplied one by one from a parts feeder or the like are adsorbed by an adsorptive nozzle composed of a vacuum pump and magnets etc., so as to be mounted at predetermined positions on the printed substrate. The electronic parts from the parts feeder are regularly transferred through, for example, a guide channel. However, there is an unavoidable slight deviation between the central axis and the feeding-out direction of the electronic parts. Due to this deviation, there would arise such problems that the electronic parts cannot be mounted at precise positions on the printed substrate even if they have been adsorbed in a constant state by the adsorptive nozzle, and that they could interfere with other electronic parts thereon.
Therefore, in an automatic electronic parts-mounting apparatus as disclosed in Japanese Patent Laid-Open No. Hei 3-52299, an adsorptive nozzle takes the electronic parts out of a parts feeder by adsorption in an adsorptive station, and a recognizing device recognizes the positional deviation of the electronic parts. Based on the recognized result, a nozzle rotation-positioning device rotates the adsorptive nozzle to determine the angular position. The electronic parts are then mounted on the printed substrate in a parts-mounting station. The nozzle rotation-positioning device does not move relatively to a rotary disc for moving the nozzle between the aforementioned stations. Namely, after the nozzle comes to and stops at the front of the positioning device by rotation, the positioning device rotates the nozzle to make a fine adjustment.
According to such a conventional technique, however, the adsorptive nozzle stops at a position of the positioning device for fine adjustment by its rotation, which would require a certain time for completion of the stopping action, thereby undesirably increasing the production time for mounting the electronic parts. Meanwhile, if it is intended to reduce the stopping time, this would make it difficult to perform the positioning precisely.
To cope with such a problem, there is known a technique in which a mechanism for rotating the nozzle itself is mounted on the head section for moving the nozzle, as disclosed in Japanese Patent Laid-Open No. Hei 3-78295. In this case, however, since the nozzle is rotated by being linked with an output shaft of the motor mounted on the head section through an intermediate member such as a belt, there would arise lost motion of the rotary transmission system which would impede accurate operation for angular positioning.